I stay with my parents in Pune. My salary has HRA component. Can I show my rent slips for the amount that I pay to my father every month and claim this deduction ?
Also why is the PAN of landlord required in case the rent is above 15000INR ?
Apart from rent slips what other documents do I need ?

You can pay rent to your father or mother (in whosoever name the house is registered) and get rent receipts signed by them.

These rent receipts can be submitted to your employer for getting HRA exemption.

No other proof is required apart from rent receipts for claiming HRA exemption.

PAN number needs to be provided in case rent amount is more than 2 lakh in a year. This is to bring the rent receiver into IT department's eyes. As 2 lakh is non-taxable income range, above which its mandatory to file income tax return. Govt may use this rent data in future to get hold of such people who have taxable income but not file returns with correct figures.